Paper punches of the type in which one or more punching elements perforate the paper inserted in the punch gap and pass through associated punch or die holes in the punch body are well known and are widely used in practically every office.
One known form of punch has a punching element or plunger which is in the form of a solid metal cylinder having essentially a flat end face the circular rim of which provides the cutting edge. In another and common form of paper punch, the punching element or plunger of this type has a groove or recess formed in its cutting end, as shown in my U.S. Pat. No. 3,987,695 of Oct. 26, 1976 (see FIG. 3). A similar construction is shown in British Pat. No. 1,544,694 (see FIGS. 3 and 4).
There is little problem in using paper punches with punching elements or plungers of known type for punching holes in a single sheet of paper, or even in a few sheets of paper inserted simultaneously into the punch. When, however, a relatively large number of sheets, i.e. a small stack, is to be punched at the same time, known paper punches require rather heavy forces to be applied and many will not work at all. Furthermore, when the punching elements of known paper punches of this type are not perfectly aligned so that they are received smoothly and exactly in the die holes in the paper punch body for receiving them, they strike the edges of the holes with their cutting edges and may become severely and irreparably damaged.
It is accordingly an object of the present invention to provide a paper punch embodying a punch element or plunger which avoids the disadvantages and drawbacks of conventional paper punches.
It is another object of the invention to provide a paper punch embodying a paper punching element or plunger having a construction such that substantially less force is necessary to punch a hole in a plurality or stack of sheets of paper simultaneously.
It is another object of the invention to provide a paper punch of the character indicated wherein the punching element is of a construction such that it does not suffer the damage encountered by conventional paper punch elements when they do not meet perfectly with the cooperating punch holes in the punch body.